Power Play: DC Power

In today’s digital era, building managers and channel professionals are increasingly open to building envelope systems that provide greater efficiency, connectivity and ease of use for building operators and occupants alike. Toward that end, direct current (DC) power is an option that’s been growing in popularity within commercial, industrial and retail applications and education, government, healthcare and other types of facilities, because DC power offers enhanced safety, manageability, sustainability and design flexibility to a building’s key electrical-based systems.

A strategic solution

Paul Savage, CEO of Nextek Power Systems, a Detroit-based DC and hybrid power solutions leader, said the inherent dilemma in modern buildings creates an opportunity for DC power.

“[Within a building’s lighting system,] all LED fixtures use DC technology but are typically powered by AC [alternating current] sources, which creates efficiency losses due to the on-site need for conversion of AC-to-DC power,” Savage said. “However, optimized low-voltage LED lamps and power server modules ideal for 24-volt [V] DC systems can deliver energy savings of up to 30 percent by avoiding this unnecessary conversion while also being safe and reliable to operate, supporting enhanced work-site flexibility and reducing labor and maintenance costs.”

Brian Patterson, president of the EMerge Alliance, a San Ramon, Calif.-based industry association that’s leading the rapid adoption of safe DC power distribution in the commercial sector, said that DC power represents a largely untapped opportunity for many facilities.

“Today’s commercial buildings use anywhere from a third to a half of all of the AC electricity produced and distributed by public utilities in the U.S.,” he said. “However, these same buildings largely use a majority of digital electronic devices that are inherently DC-powered—from electronic ballasts, LED lighting and lighting sensors and controls to HVAC controls and actuators and a range of computer/IT/telecom equipment—which requires more AC power to be converted to DC at the device level in order to power them.”

An increasing amount of native DC power generated from renewable-energy sources—such as solar and wind—must be converted to AC electricity to be compatible with existing AC distribution methods.

“These conversions, in both directions, result in significant losses of electricity and associated wasted energy and also add to the complexity and reduced reliability of the overall electrical system,” Patterson said.

A DC power technology approach is competitive with other low-voltage building strategies such as power over ethernet (PoE), which passes electrical power along with data on ethernet cabling. This allows a single cable to provide both data connection and electrical power to such devices as wireless access points, phone systems, IP cameras and LED lighting. However, Savage said DC power technology has dropped in price by nearly one-third over the past five years, making it a more attractive option on a first-cost basis, and that it offers a number of other benefits as well.

“Based on the Class 2 nature of the system, DC power is intrinsically safer to work with than AC power and can therefore be installed by less-costly contractor personnel, which saves time and money and makes more productive use of an electrical contracting firm’s total workforce,” Savage said.

Thanks to the cutting-edge DC technology currently available, buildings can individually dim outputs so that connected fixtures can be fielded without a driver in the fixture, a component which has long been considered the weakest part of the LED system. While Savage acknowledged that the installation of DC power technology may not be as quick and inexpensive as a one-for-one tube replacement in a lighting upgrade, the savings are greater, especially when the upgrade involves the further incorporation of lighting controls.

“Building owners can save $1 to $2 per square foot for a DC-controlled solution, wired or wireless,” he said.

A Class A office renovation using DC lighting

A real-time example

Bedrock Real Estate Services, an affiliate of Quicken Loans, has established itself as a leading full-service real estate firm specializing in commercial space in the Detroit area. Thanks to a recent lighting upgrade using dedicated AC-to-DC power conversion technology, Bedrock achieved significant energy savings, maintenance reductions and improvements in lighting system quality and flexibility at its century-old Chrysler House facility in Detroit.

Seizing an opportunity to upgrade the structure’s conventional three-lamp fluorescent T8 lighting configuration to more modern LED technology to save money, reduce labor and maintenance requirements, and enhance end-user control, Bedrock also hoped to remedy the building’s overlit environment with a solution that delivered optimal light levels and a pleasing ambiance for its occupants.

Following the installation of 24V DC LEDs; 24V DC power server modules; Class 2, safe-to-the-touch 24V DC plenum-rated wiring; and a wireless control system providing both occupancy and daylight dimming control, Bedrock saw energy consumption within its upgraded areas fall by 40 percent or more.

Along with these energy and cost savings, Scott Collins, Bedrock project director, was equally excited about the reduction in up-front labor requirements driven by the upgrade.

“With traditional lighting systems, it can take 1–2 hours to do the rough-in and installation for each fixture, but with our low-voltage DC lighting and control system, the system was all-in-one and literally took just minutes for installation compared to AC fixtures,” he said.

“Ultimately, while it looks the same from the outside, DC power technology can deliver more lumens per watt and, therefore, better light levels and CRI than any AC system because it streamlines the electrical delivery system means and avoids unnecessary power conversions on the way to delivering light,” Savage said.

Benefit from DC power

Following, industry experts share tips for contractors considering the use of DC power technology in a building upgrade.

Identify ideal candidates: “Some of the best candidates for DC power technology include larger projects pursuing deep lighting retrofits that involve gutting a building and/or putting in a new ceiling,” Savage said. “While contractors don’t have to touch the wiring when directly replacing fluorescent tubes with LED tubes, the opportunity to save energy costs is also less in those situations, such that the installation of DC power technology can drive greater savings than a simple lamp replacement.”

While the use of DC power technology is still uncommon, Savage is seeing more interest in this approach.

“[Interest is growing] especially among the most efficiency and sustainability-minded companies, which represent a growing sector of the commercial market,” he said.

Understand the economics: Much like LED lamps and lighting controls, DC power technology is currently rebated on by a broad range of U.S. utility companies and represents an attractive financial incentive that can help offset the upfront cost of these projects, reduce their payback period, and further enhance their return on investment.

“Financing companies also recognize the role DC power technology plays in improving a building’s energy efficiency, reliability, sustainability and ultimate valuation,” Savage said.

Control the process: “[While DC power] isn’t something the average building owner is shopping for—it’s usually specified or recommended by a contractor—it’s becoming more of a standard option in the bidding process,” Savage said. “Years ago, during a building’s design stage, DC power technology was often offered as an alternative bid, but now, more and more larger projects are presenting this technology as the base bid. Because electrical contractors can have a lot of influence on this decision, we advise them to do a favor for their clients by proposing this approach for their consideration. Building owners like to be introduced to new technologies, so it’s a good and proactive message for contractors to bring.”

Explore hybrid opportunities: “Building technologies that are run on variable-speed platforms, such as motors, will increasingly require DC power as opposed to AC power so that they can be electronically adjusted,” Patterson said. “Overall, there are blocks of electricity usage in a building that can be converted to DC power, like lighting, security systems, air handlers, etc., but the whole building doesn’t have to be converted to DC technology. We’re seeing more and more ‘hybrid’ systems employed in which some technologies are on DC and some are on AC power. In the end, the use of multiple systems can enhance building resiliency by protecting against blackouts, brownouts and downtime.”

Embrace a new paradigm: “With the recent explosion of the internet of things and a growth in the number of low-voltage devices used in the modern building, including cameras, sensors, actuators, etc., it’s not just about lighting and HVAC in buildings anymore, but about customizing the whole environment for occupants based on the time of day, the type of work being done, and the individual themselves,” Patterson said. “Buildings are becoming more active in harvesting energy back into the electrical system to power all of its things, and DC power technology is yet another tool that will enable buildings to come into the ‘Electro-Active age.’”

Get smart: Patterson said ECs should learn about DC power technology through in-person training or online webinars offered through an industry alliance such as the EMerge Alliance (www.emergealliance.org) or a manufacturer/service provider such as Nextek (www.nextekpower.com). Also, stay on top of the latest codes, because future technology will materialize through code revisions.

“Energy storage and resilient systems are becoming increasingly important to building professionals as more and more devices and strain are being placed on building systems, so it’s great for contractors to explore and familiarize themselves with the low-voltage world of applications below 120V, such as 48V, 24V, 12V and even 5V [USB ports],” he said.

The time is now: “People think that this technology is about the future, but it’s happening now and will continue to transpire at an increasingly fast pace,” Patterson said. “Between now and 2030, we’ll be seeing big changes in the way buildings use electricity. It’s a change-oriented era today, and time spent learning about what’s happening out there is time well spent.”

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